Electric condenser construction



May 5; 1936. B` G 0| V|NG 2,039,340

ELECTRIC CONDENSER CONSTRUCTION Filed April 7, 1933 '6 Sheets-Sheet l My5, 1936- B. G. oLvlNG 2,039,340

ELECTRIC CONDENSER CONSTRUCTION Filed Apvril "l, 1933 3 Sheets-Sheet 2May 5, 1936. B. G. oLvlNG 2,039,340

E RIG CONDENSER CONSTRUCTION NNNNNN OR Patented May 5, 1936 ELECTRIC(CUNDENSIER CUNSTBEUTIN Bror G., llving, Hamden, @onus assigner toProducts Protection (Corporation, a corporation of Deiaware Thisinvention relates tov electric condenser construction and to a method ofproducing -the same.,

@ne of the objects of this invention is to provide a thoroughlypractical, inexpensive and efficient electric condenser construction.Another object is to provide a condenser construction, adaptedparticularly for functioning on alternating current circuits and at highvoltage in whichheat dissipation will be eifectively takenfcare of andthe otherwise undesirable limiting effects of dielectric heat lossessubstantially negatived. Another object is to provide a condenserccnstruction in which the space factor will be greatly improved and inwhich accordingly the k. v. a. capacity of the condenser per unit volumewill be high. Another object is to provide a condenser construction ofthe above-mentioned nature which will be strong, compact, durable and reliable in action. Other objects will be in part obvious or in partpointed out hereinafter.

The invention accordingly consists in the fea tures of construction,combinations of elements, arrangements of parts and inthe several stepsand relation and order of each of the vsame to one or more of theothers, all as will be illustratively described herein, and the scope ofthe application of which will be indicated in the following claims.

In the accompanying drawings, in which is shown a preferred embodimentof the electrical features of my invention,

Figure 1 is a. vertical central sectional view through a completelyassembled condenser;

Figure 2 is a horizontal sectional view as seen along the line 2-2 ofFigure 1; L

various sections;

Figures 5 and 6 arel comparative illustrative condenser constructions,and

Figure 7 shows comparative operating graphs.

Similar reference characters refer to similar parts throughout theseveral views in the drawings.

As conducive to a clearer understanding of certain features of myinvention it may here be pointed out that, in the design andconstruction of electric condensers, particularly condensers whichemploy insulating tissue, as in foil condensers, impregnated withcertain liquid impregnating materials, the dielectric losses in theinsulating material become of such magnitude that it has heretofore beenfound difficult appropriate- 1y and eiiiciently to reconcile the factorsof oli-2 electric strength and ci heat-dissipating surface with respectto such factors as the voltage and frequency and lr. v. a. capacity perunit volume oi. the condenser. For example, where the con-1 denser isemployed in a direct current circuit, the total volume of the condenseris a function of' the dielectric strength orthedielectric employed, lthevolume of dielectric reduired per k. v. a. being proportional to thesquare or the operating gradient. Where, however, the. condenser is tofunction on an alternating current circuit, the dielectric losses becomean important factor and the volume of dielectric Aemployed may be saidto be a function of both the dielectric strength and of the dielectricloss. The dielectric losses are, of course, in turn a function of thefrequency. The dielectric loss, particularly with the use of certaindielectric material such as condenser tissue impregnated with liquidimpregnating materials, becomes of such magnitude that the resultant orrequired heat-dissipating surface determines the physical dimensions ofthe condenser and hence full advantage cannot be taken of thedielectricstrength cf the dielectrios employed'. n

One of the dominant aims of this invention is to provide a condenserconstruction in whichappropriate heat dissipation and hence dissipationof the dielectric losses are dependably achieved while at the same timeachieving high k. v. a. capacity per unit volume and effectiveinsulation without sacrifice vo1 the advantages of the dielectricstrength of the dielectric employed.

Referring first to Figures 1 and 2, I have shown a casing l0 of anysuitable construction, together with a suitable insulating medium. Byway of illustration, the casing l0 may consist of a cylindrical pressedsteel casing or tank in which the side walls I0 and the bottom. lllb arepreferably formed integrally with one another, the

closure Il).c being applied as described hereinafter.

Inasmuch as I have elected to illustrate the electrical features of myinvention in coaction with a dielectric medium that is in the form ofagas, suchas nitrogenffor example, under a pressure on the order of 15atmosphereslprefer to employ the casing construction just mentionedinasmuch asl that casing construction is well adapted to withstand suchheavy internal pressures.

The central portion Aof the clos'ure` I0 is provided. with a threadedopening II to receive a supporting rod I2 preferably of steel, the partsbeing so related that when the closure Illc is in closing position, therod li'. is substantially coaxial with the axis of the casing I0.Preferably the rod I2 is welded to the closure Ill'2 as at I3 in orderto insure air-tightness.

Adjacent its upper end, as viewed in Figure l, the supporting rod I2carries a collar Il pinned thereto as by the tapered pin I5 and abuttingagainst the collar, is a spider-like support genn erally indicated atI6, preferably made of a suitJ able insulating material such asbalrelite. The spider I6 has a central, collar-like portion l0 whichabuts against the collar I4 on the rod lil, these two parts being shapedin any suitable Way as is indicated at I1 to prevent rotation oi thespider IB relative to the collar Ill and hence relative to the casingitself.

Extending radially from the collar portion itisL is a suitable number ofsupporting arms, illustrew tively four in number, and 'they are bettershown in plan in Figure 2 at IBb, IB, IE and lf. These arms are givenany suitable cross-section adapted to give them substantial rigidity orresistance to bending out of their common plane.

At the lower end, as seen in Figure i, the supporting rod I2 carries asomewhat similar spider' member generally indicated at lll; the latteris also provided with a central collar-like portion lilll which isslidably received on the rod il and it has also radially extending arms,preferably four in number, similar to the arms of the spider IS; inFigure l two of these arms areshown in cross-sec tion at Il!c and IEE.

Between the arms of the spiderdike :frames it and I8, my condenserconstruction is adapted to be supported in a manner more clearlydescribed later; the condenser construction, made up oi a plurality ofsections, is virtually clamped between the frames IG and I8, a nut IBthreaded onto the lower end of the rod I2 coacting with the latter 4todraw the frames I6 and I8 toward each other and thus securely hold thecondenser sections in place. The nut I 9 may be locked by any suitablemeans, such as a cotter pin 2li.

By Way of illustration my condenser construe tion is made up ofconcentric annular sections, Illustratively live in number; they areindicated in Figure 1 at Si, S2, S3, S4 and Ss. And to illus tratecertain features of my invention, let it be assumed that theelectrostatic capacity or 'the k. v. a. rating of these sections are thesame and let it be further assumed that the sections are to be connectedin series. Illustratively, the condenser may be intended to functionat22,000 volts on a. (iO-cycle alternating current circuit.

. The condenser sections are preferably made by spirally Winding twofoil strips and two strips oi insulating material, alternated with eachother,

the insulation strips having their edges alined while the foil stripsare staggered with respect to each other, one foil strip projecting toone side beyond the adjacent alined edges of the insulation strips andthe other foil strip projecting beyond the alined adjacent edges of theinsulation strips on the other side; these relations of these parts areclearly indicated in Figure 3 with respect to each of the various coilsections, the foil strips being i Y indicated at F1 and F2 and theinsuiaung strips being indicated at I1 and I2. The insulating strips maybe made up of condenser tissue which may be impregnated with anysuitable liquid or solid dielectric mpregnating material or materials.

The various condenser sections are Wound upon suitable cores, shown inFigure 3 at C1, C2,

Ca, (lli and Us; these cores are ol? an axial dimension. somewhatgreater than the oveiwail axial dimension of the wound. i'oil and paper.strips and hollow cores are o1 progressively increasing diameters. Inorder to achieve equal ity oi electrostatic capacity throughout all oithe condenser sections, the number oi turns oli alter-- nated ioilstrips and insulation strips progressively diminishes as the insidediameter ci the annular condenser sections, as determined by the outsidediameters oi? their respective cores, increases. The number of turns, inorder to acliieve equality, is proportional to the inside diurni-iter ofthe condenser section except later noted.

The cores Ci, C2, etc., are preferably in the torni i ol. relativelythimwalled tubingl and. they may be rely of solid dielectric mattia oimade of solid dielectric material, the

suitable layer oi' insulating' material is :il si a plied to the outsidesurface of the tubular incl l cores and then the winding 'may be'proceeded with.

When the winding of each condenser section ou its core has beencompleted, the windt o" each coil section are held against unwind: byany suitable means, such as, for example, by taping the outer peripherythereo", or winding a suitable number oi turns of sheet dielectric aboutthe outer periphery or by applying thereto a suitable tubel likedielectric sleeve; this outer binding insulating material or member isshown in Figure 3 at B.

The various sections, tlius constructed, are, iiutherrnore, soproportioned, t, nears cl from liligures l and 1i, that when ...my arear ranged one within the other so that their aires coincide, there isprovided an annular space bc tween the outer cylindrical surface of onesection und the inner cylindrical surface oil' 'the core of the nentlarger section. Thus arranged, tbc various sections are held in thisrelation and in these relative positions by the arms of spider framesIll and I8, the arms being provided with suitable grooves G (see Figurel) suitably spaced il with respect to the support l2, the sections maybe electrically interconnected in any suitable manner as may benecessary or required by 4the particular electrical conditions to beinet with in practice. For example, the sections may be connected inseries and when they are thus to be electrically intei1elated, I preferto employ eleotrical interconnections such as are shown lugm ure fi.

Turning now to Figure 4, one terminal or elec trode of the innermostsection .Si is grounded to the frame or casing as by the conductor Elwhich, as is better shown in Figure l, may be grounded directly to therod support I2. A suitable conductor 22 (Figure 4) connects the otherterminal of section S1 to one terminal of the outermost section S5, theremaining terminal or electrode of which is connected by a conductor 23to one terminal of the next innermost section S2; the remaining terminalof section S2 is connected by conductor 24 to one terminali of the nextouterlill lli)

liti

accesso most section Si, the remaining terminal of which is connected byconductor 25 to one terminal of the middle section S3; the remainingterminal of section S3 is connected by conductor 26 to a high voltageterminal bushing 2l (Figure l) which carries the conductor through thewall of the closure member itc, the insulating terminal construction 2libeing of any suitable design or construction.

11 The closure member IGC, thus carrying the terminal bushing and thecondenser, is now related to the casing it, the lower end of the rod i2being received in an opening dll in the bottom lill so that the rod [Itfinds itself supported at its ends by the bottom and closing walls luband itc of the -container. The lower end of the rod it is preferablywelded about the periphery of the opening 3l and to the bottom iilb, asis indicated at 38, thus to make a dependable air-tight joint. Theclosure member we may now be secured in place. The closure iic ispreferably dimensioned to be received within the open end of thecylindrical side walls i il of the container, whereupon the upper edgeportions oi the latter are hammered or bent over as at lild (Figure l)and then welded as at 39 to make a hermetic seal or joint.

The insulating and cooling medium may thereupon be placed in thecontainerv and where that takes the form oi a gas under pressure, it maybe injected through a nipple 4i! threaded into the upper end oi thesupporting rod i2, the parts being provided with suitable channels orpassages opening into the interior of the sealed casing; the

parts may also be so constructed that the nipple 40 supports a gage iiito indicate the pressure ai the gas within the container.

Referring now again to Figure l, the assembly thus achieved will be seento provide a central annular passage P1 and an outer annular passage P2while intervening the successive concentrically arranged sections areannular passages Pa, P4, Ps and P6; all' of these passages will be seento be connected with each other at both their upper and lower ends.Whatever the dielectric cooling medium employed, whether gas underpressure or otherwise, there is thus provided adequate and efficientcirculation thereof into thermal contact with the condenser sections,thus to withdraw the heat from the latter and to dissipate the heat tothe walls of the casing lll for radiation or other withdrawal therefrom.The heat losses in the condenser sections are transferred to thedielectric cooling medium, for,example, the gas under pressure, that ispresent in the passages P1, P3. P4, Ps and Pe; the medium thus becomingheated rises (as viewed in Figure l), thus causing it to flow intocontact with the upper wall IIJc of the casing and thus'causing theiluid medium to now downwardly in the passage P1 where it further givesup heat to the side walls Illa of the casing; continuing its circulatingpath, it moves downwardly and thence inwardly in a radial direction, incontact with the bottom wall Illb of the casing to which it gives upfurther heat, whence it is ready to` enter the lower ends of thepassages P1. P3, P4, P and Ps in a cooled condition, thus to repeat theabove-described path of flow and heat abstracting and dissipatingaction.

In this connection, lit is important to note that, by the structuralfeatures above described, I am enabled to take full advantage of thedilectric strength of the dielectrics employed, whether they be in theform of the insulation strips which are alternated with the foil platesof the condenser sections or in the form of the cylindrical core membersC1, Ca, etc.; as the inside and outside diameters oi the successivesections increase, the heat-dissipating surfaces thus/ furnished thesections increase. Assuming the sections to be of the same k. v. a.rating, and assuming that the innermost section S1 is initiallydimensioned as to outside and inside diameters to provide an appropriateheat-dissipating surface to take care of the heat losses such as thedielectric losses, the heatdissipating surface per k. v. a. of theremaining and. successively larger-diametered sections increases withincrease in the inside diameter thereoi'. Thus, am enabled to increasethe electrical operating gradient of these outer or successivelylarger-diameterecl sections, thereby correspondingly decreasing theamount oi' solid dielectric material that need be employed, with theresult that the volume of solid dielectric required per k. v. a.decreases as the inside diameter of the sections increases. lFhe eiectoi this important result is far-reaching. For example, l am enabled toutilize the full eillciency of the solioldielectric material employedand, contrary to heretofore known practice, l am enabled to determinethe volume of solid dielectric material employed per k. v. a. by itsdielectric strength and not by the heat losses of the dielectric. Stateddifferently, where prior practice has to depend upon the necessary guideor rule that the volume ofsolid dielectric is a function of both thedielectric strength and the dielectric loss in the dielectric employed,the volume oi the solid dielectric employed is, in accordance with thefeatures of my invention, determined by only the one factor, namely, thedielectric strength of the dielectric employed.

These important considerations further make it possible to achieve anunusually good space factor, resulting in a small volume per k. v. a.The amount of solid dielectric material employed is greatly reduced andwhere condenser tissue and an impregnating material are employed, theamount of both is materially reduced and this reduction is of verysubstantial importance because of the relatively very expensiveimpregnating materials that sometimes must be employed to achievecertain results. l

In view oi the foregoing, I believe the practice of my invention will beclear but as conducive to a clearer understanding and a more readyappreciation of various features of my invention, it may be helpful toconsider certain illustrative comparative constructions; hence,reference might now be made to Figures 5 and 6, Figure 6 indicatingdiagrammatically certain aspects of ,-.my invention as compared toFigurq5 which may be 'considered as .illustrative of prior practice.

In Figure 5 I have shown diagrammatically and in vertical cross-sectiona condenser roll A made up of alternated foil andinsulation stripsrolled into a helix having an outside diameter D1, an inside diameterD2, and a thickness or width in an axial direction W. Let it be assumedthat the capacitor roll A of Figure 5 is intended to function at avoltage of 2300 volts and that it is designed and related so that themaximum safe operating temperature is reached at an operating Volumeoccupied by dielectric-.. 660 cubic inches Total weight of dielectric66lbs. improved eiliciency of use of condenser tissue Total rating ofcoil at a gradient of 300 or solid dielectric material.

volts per mil 22 lcv. a. If each roll B and C is to dissipate not morePower factor oi' dielectric at operating temthan 0.115 Watts per squareinch of exposed surperature 0. 3%- iace, and since the exposed areas ofrolls B and Total loss in roll 100 -66 watts Exposed surface(heat-dissipating areal- =126+314+66+66=572 sq. in.

Assuming that the fluid employed as a dielectric and cooling mediumisyable to remove or dissipate approximately 0.01 watt per square inchper degree C. rise in temperature, then the temperature differencebetween the roll A and the fluid is approximately 10 C.; taking intoconsideration the temperature difference between the fluid and the tankor casing and between the tank and the surrounding air or atmosphere, itmay, for present purposes, be assumed that this is the maximumtemperature rise to which the roll A may be subjected without danger ofthermal breakdown.

Turning now to Figure 6, let it be assumed, for purposes of comparison,that, in accordance'with certain features of my invention, the roll A ofFigure 5 has been subdivided into two concentric rolls of equal volume,namely, rolls B and C (Figure 6). The dimensions Di, D2 and W are again,respectively, 10", 4" and 10", and to sim plify the computations let thedimension D3 be 7.6", being square root of the mean value of the insidediameter and outside diameter squared, oi rolls C and B, respectively,inasmuch as the radial thickness of the annular passage P between therolls may be assumed to be relatively small. The followingcharacteristics result:

volume of rou B (one-half of roll A of Figure 5) 330 cubic inches Volumeof roll C (one-hall.' of

rou A of Figure 5) 33o cubic imanes' Exposed area of roll B isN64-2238+615- 430 sq. in.. Exposed area of roll C is 238+3l4+tL 618 sq.in. Total exposed area of rolls B and C-- 1048 sq. in.

It will be noted that the total exposed area has thus been increasedfrom 572 square inches for roll A of Figure 5 to 1048 square inches forthe arrangement of Figure 6.

lowing the same temperature rise (10 C.) in rolls B and C as in roll A,0.115 Watts can be dissipated per square inch and. hence the total heatloss that ean'be dissipated from rolls B and C is 1048x0115 or 120watts, corresponc'lm ing, therefore, to a total rating of 40 k. v. a. ata power factor of 0.3%.

It will be noted that the total rating has been increased from 22 k'. v.a. for roll'A of Figure 5 to 40 k. v. a. for the arrangement of Figure 6in which, for illustration, the roll A of Figure 5 f-g or a ibs. (form11 A) to se or 1.65 lbs.,

thus illustrating, among other things, the greatly C do not happen to beequal, roll B should not be rated at more than @X 0I' 16.4 k. V. 81.

and roll C should not be rated at more than 68o 10AX40 or 23.6 lr. v.a.,

the ratings thus being made directly proportional to theheat-dissipating areas.

Now, in accordance with certain features of my invention earlierabove-mentioned, the rolls B and C are to be operated at differentgradients, thus to load each of them to their respective maximum safelimits. Roli B of Figure 6, which contains` half the volume of roll A ofFigure 1, would carry a load of 11 lr. v. a. (half o the rating of rollA) at a gradient of 300 volts per mil (the latter being the actualoperating gradient of roll A) to allot to roll '.B a rating of 16.4 lr.v. a. (as above arrived at), the operating gradient of roll B should beAsoo 1 5- or 366 volts per mil. Roll i3, rated, as above arrived at, at23.6 ir. v. a. and also being lialf the volume oi roll A, shouldtherefore have an opern ating gradient of 300 N/zac or 43d volts permil. To 4provide these different operating gradients, diilerentthicknesses of dielectric are employed. At 2300 volts, the thiol-r nessper layer (of strip or sheet insulation between the toil plates) in rollE at the operating gradient oi 366 'volts per inil is 6.3 mils and thethickness of dielectric per layer in roll C, at a gradient of 438 voltsper inil 5.25 mils. Ii" con denser tissue oi 0.1i inils thicknessemployed, sixteen vtl'ilcknesses or Webs oi" condenser tissue are usedper layer in roll E. but only thirteen Webs or thicltnesses per layer inroll. C. The electro static capacity ci roll B is then 8.2 inicroiaradsand that of roll is lill inicroiarads.

The above illustrative and comparative figures and data show certain oithe unique advantages flowing from my invention and the speciiicinstance above developed suffices Where the capacities formed by therolls lEi and C are to he connected in parallel.

Where the rolls are to be connected in series for 4600 volt service(instead oi parallel above mentioned for 2300 volt service), severalspecfic or detailed steps may be taken in carrying out my invention. Forexample, still considering the illustrative and comparative structures0I Figures 5 and d, ll may malte the electrostatic capacities oi. thesections or rolls B and. C equal (in order to avoid inverse distributionof voltage drops) and use a diiferent dielectric layer thickness in eachroll or by Way of further example I may use the same thickness of.dielectric layer in all the sections or in rolls B and C but pro portionthe electrostatic capacities of the rolls so that the terminal voltageacross each roll provides the desired operating gradient in Ithat roll.

To illustrate these illustrative embodiments of Gil aoeasw my invention,let the ,rst above-mentioned of these be iirst considered. Where, asearlier above outlined, the capacities of rolls B and C were,respectively, 8.2 microfarads and 11.8 microiarads, the voltage of 4600,if applied to these two rolls connected in series, would divide betweenthe sections or rolls inversely as their capacities and hence thevoltage across roll B would be 2710' volts and the voltage across roll Cwould be 1890 volts and roll B would draw a load of 22.8 k. v. a. whileroll C would draw a load of 14.7 k. v. a. However, by decreasing thenumber of turns in roll C so that its electrostatic capacity is reducedfrom 11.8 to 8.2 microfarads, thus making the capacities of, the tworolls B and C equal, the two rolls, now connected in series, would causethe voltage to divide equally between them and the rating or loadcapacity of each roll becomes 16.4 k. v. a. The total rating thusbecomes 32.8 k. v. a. Sixteen webs of 0.4 mils condenser tissue are usedin roll B to make up a single layer of insulation between adjacent foilplates and thirteen webs to make up a singlelayer of solid dielectricinsulation in roll C.

As compared tothe condenser A oi Figure 5, this series arrangement ofrolls B and C, aside from achieving the above-mentioned advantages,achieves an increase in capacity or rating from 22 k. v. a. (condenseror roll A oi' Figure 5) to 32.8 k. v. a. while also actually achieving asubstantial saving in materials employed, the saving in the latterconnection being equivalent to the difference between 40 k. v. a. and32.8 k. v. a. Actually the cost of material per k. v. a. has beenreduced turing conditions or circumstances where it may be desirable, asa manufacturing expedient, to maintain the same thickness of dielectriclayer in both rolls or in the several sections.

In such case, considering iirst sections or rolls B and C of Figure 6 ascompared with the roll A of Figure 5 and, as first above indicated byillustrative calculations, roll B may have va maximum of 16.4 k. v. a.and roll C a maximumrating of 23.6 k. v. a.; ii these two sections areconnected in series across a 4600 volt circuit, and it is desired tooperate both rolls at their maximum rating, the electrostaticlcapacities of the two rolls B and C should be so proportioned that thevoltage across roll B, in order to obtain 16.4 k. v. a.. becomes 1890volts, and the voltage across roll C, in order to obtain 23.6 k. v. a.,becomes 2710 volts. As the voltage across two series-connected rollsdivides between the sections inversely as their capacities, theelectrostatic capacity of roll B, rated at 16.4 k.'v. a. and 1890 volts,must be made approximately 12.4 microfarads, while the capacity of rollor section B, rated at 23.6 k. v. a. and 2710 volts, should beapproximately 8.4 microi'arads.

In order now to obtain a rating of 16.4 k. v. a. in roll B, theoperating gradient, as earlier above calculated, is 366 volts per mil.The layer thickness oi dielectric or oi' condenser tissue is then or5.17 mils, requiring therefore thirteen lwebs of 0.4 mils condensertissue per layer of dielectric. Inasmuch as the same thickness ofdielectric is or approximately 525 voltsper mil.

inasmuch as it has been assumed, in the forelgoing, that the impregnatedtissue or dielectric employed can withstand a stress oi 600 volts permil, provided the temperature does not rise above a safe limit, it willbe seen that the operating gradient of 525 volts per mil above arrivedatfalls within this operating limit of the dielectric and that the roll Cas illustratively calculated above is satisfactory.

The above several calculations and embodiments are to be understood asillustrative and are not to be interpreted in a limiting sense, beingintended to possibly clarify certain features or aspects of my inventionand to aid in arriving at a more ready understanding of certain aspectsof my invention. Moreover, the comparative figuros above given indicatevarious of the many thoroughly practical advantages that new from myinvention; by sub-division beyond the illustrative two sections ofFigures 6, these -advantages. are multiplied.

In order further to clarify certain aspects of my invention, it might benoted that, particularly with electrostatic condensers whose dielectricis impregnated with liquid hydrocarbons, such as oil, and the like, thedielectric loss or power factor varies with the operating temperature,increasing relatively rapidly as the operating temperature increasesabove approximately40 C. This characteristic is graphically indicated inFigure 7 by curve X in which the rise in temperature beyond about 40 C.will be seen to be relatively rapid.

This characteristic indicates and is in lfact caused by cumulativeeffects inasmuch as the heat losses, increasing with the temperature,cause further rises in temperature and in turn cause further increasesin the losses. action tends to give rise to the creation of sooalled hotspots wherein thermal'and ultimate electrical breakdown occurs.

Even though iibrous materials impregnated with, for example, a liquid orsemi-solid impregnating materia-l, such as oil or the like, have highdielectric strength, it has heretofore not been possible efficiently orpracticably to take' advantage of its high dielectric strength since thek. v. a. rating (proportional to the square of the operating gradient)of the condenser is limited by the temperature rise, as will be clear inwhat has just been stated above in connection with the characteristiccurve X of Figure 7.

However, by practicing my invention, I achieve not only the manifold andimportant practical advantages earlier above indicated but also, as Willbe clear particularly from Figure 1, I am enabled to provide such alarge area oi' contact between each condenser section and the dielectriccooling medium that the rate of heat dissipation is sufficiently high tomaintain the eiective operating temperature at or. relatively near thepoint oi' minimum dielectric loss on the curve X of Figure 7.

'Ihe axially projecting ,cores C1, C2 project beyond the sides of thecondenser sections suil'iciently to formsuitable voltage barriersbetween the exposed or projecting foils of adjacent 'sections; theyproject to a large enough extent to prevent surface leakage orflash-over from one SuchI condenser section to another. Where, as in thepreferred form, a gaseous dielectric under high pressure, is employed,the gaseous dielectric, of relatively high dielectric strength,permeates and enters into any pores in the solid dielectric man terialemployed and improves the latter. The gaseous dielectric, furthermore,has a permittivity on the order of unity whereas the solid dielectricmaterial such as that employed in the cores C1, Cz, etc., when thelatter are thus made, has a much higher permittivlty, but these twodielectrics are in series between adjacent sections of the condenser andbecause of the distribution of the dielectric stress between adjacentsections inversely as the permittivities of these two serially relateddielectrics, the annular space between adjacent sections may be madeless and this factor may also be utilized to contribute toward achievinggreater compactness and a better space factor.

The manner in which the condenser sections are interconnected whenconnected in series, as was above described in connection with Figure 4,also contributes toward improving the oven-all space factor for theinnermost and outermost sections are of relatively lowest voltage whilethe potential of the sections increases as the middle section orsections are approached; this modeoi connection of the sectionsdiminishes the potential difference between the outermost section andthe walls of the casing and the spacing between these two parts maytherefore be made less.

It will thus be seen that there has been provided in this invention acondenser construction and a method of achieving the same in which thevarious objects hereinbefore mentioned, together with many thoroughlypractical advantages, are successfully achieved. It will be seen thatthe condenser is of high efficiency in that li am enabled to make highlyeilcient use of the c'iielecm tric strength of the solid dielectricsemployed while maintaining correspondingly a minimum possible volume ofsuch solid dielectrics, thus greatly reducing the dielectric losseswhich become evident in the form of heat. Moreover, it will be seen thatI am enabled to achieve great economy in such matters as cost ol'production, while economy is also achieved by reason of the high ratioof k. v. a. capacity per unit volume. Thus, I am enabled to achieve acondenser construction well adapted to meet the varying conditions ofhard practical use in alternating current circuits.

As many possible embodiments may be made of the mechanical features ofthe above invention and as the art herein described might be varied invarious parts, all without departing from the scope of the invention, itis to be understood that all matter hereinabove set forth or shown inthe accompanying drawings is to be interpreted as illustrative and notin a limiting sense.

I claim:

l. In condenser construction, in combination, a casing, a substantiallycentrally positioned vertical supporting member in said casing, a pairof spaced frame members carried by said supporting member, said framemembers having a plurality of radially extending arms, a plurality ofannular concentrically related condenser sections extending about saidsupport and between said frames, the outside diameter of a smallersection being smaller than the inside diameter of the next adjacentsection, thereby to provide an annular passage between adjacentsections, the over-all dimensions of said concentric sections as a wholebeing smaller than the inside dimensions of said casing, whereby saidannular passages are in communication with the spaces above and belowthe condenser sections and with the space between the outermostcondenser section and the inner wall of said casing, said arms engagingand holding said sections inconcentric relation, and a dielectriccooling medium in said casing for circulation through said passages andsaid spaces.

2. In condenser construction, in combination, a casing, a substantiallycentrally positioned vertical supporting member in said casing, a pairof spaced frame members carried by said supporting member, said framemembers having a plurality of radially extending arms, a plurality ofannular concentrically arranged condenser sections about said support,the outside diameterof a smaller section being less than the insidediameter of the next larger section, each section having a centralcylindrical core projecting beyond its ends and said arms having groovesfor receiving the projecting portions of said cores, thereby to holdsaid sections in assembled relation, a dielectric cooling medium in saidcasing for circulation through the annular passages be tween adjacentsections, and means for drawingl one of said frames with its arms towardthe other frame and its arms, thereby to clamp said seotions in positiontherebetween.

In condenser construction, in combination, a casing, a substantiallycentrally positioned vertical supporting member in said casing, a pairof spaced frame members carried by said supporting member, said framemembers having a plurality of radially extending arms, a plurality oiannular concentrically arranged condenser sections about said support,the outside diameter of a smaller section vbeing less than the insidediameter of the next larger section, each section having a centralcylindrical core projecting beyond its ends and said arms having groovesfor receiving the projecting portions of said cores, thereby to holdsaid sections in assembled relation, a dielectric cooling medium in saidcasing for circulation through the annular passages between adjacentsections.

fl. In condenser construction, in combination.

` a casing, aplurality oi annular concentric confdenser sections ofprogressively increasing inside and outside diameters proportioned sothat there is an annular space between adjacent sec tions, each sectioncomprising two foil strips and two dielectric strips alternated witheach other` and arranged splrally, the inside and outside diameters ofsaid sections being so large that the exposed surfaces of the annularsections provide such large heat-dissipating surfaces that the factordetermining the solid dielectric material employed in the sections isthe dielectric strength ci. the dielectric material and not the heatlosses in the dielectric at the frequency of operation ci' thecondenser, and a fluid dielectric and cooling medium for circulationthrough said annular spaces and into contact with the casing.

5. In condenser construction, in combination, a casing, a plurality ofannular concentric con denser sections oi.' progressively increasinginside and outside diameters proportioned so' that there is an annularspace between adjacent sections, condenser sections progressively moreremote from the innermost annular section having progressively greaterheat-dissipating surfaces and progressively smaller quantities oi soliddielec tric material therein, and a fluid dielectric and cooling mediumfor circulation through said annular spaces and into contact with thecasing.

icv

6. In condenser construction, in combination, a casing, a plurality ofannular concentric condenser sections of progressively increasing insideand outside diameters proportioned so that there is an annular spacebetween adjacent sections, said sections comprising foil plate elementsand sheet condenser tissue impregnated/With a dielectric materialalternated with the foil plates, the volume per k. v. a. of impregnatedcondenser tissue in said sections being progressively less from theinnermost section to the outermost, and a fluid dielectric and coolingmedium for circulation through said annular spaces and into contact withthe casing.

'7. In condenser construction, in combination, a casing, a plurality ofannular-like condenserl sections each of substantially the samecapacity, said sections being arranged one about the other andsubstantially coaxially and being dimensioned to provide spaces betweenadjacent sections, means mechanically supporting said sections Withinsaid casing, means electrically connecting said sections in series sothat a middle section is of substantially highest voltage and theoutermost sec- `tion that is closest to the casing walls is ofrelatively low voltage, and a fluid dielectric and cool- Y ing mediumfor circulation through the spaces between sections and into thermalcontact with the walls of the casing.

8. In condenser construction, in combination, a casing, a plurality ofannular-like condenser sections each of substantially the same capacity,said sections being arranged one about the other and substantiallycoaxially and being dimensioned to provide spaces between adjacentsections, a metallic supporting member within said casing, saidcondenser sections being arranged about said supporting member, thelatter being dimensioned relative to the innermost section so that thereis provided an annular space there` ly to said supporting member and thewalls ofA said casing, are of relatively lowest voltages.

'9. In condenser construction, in combination, a plurality of condensersections having progressively larger heat-dissipating surfaces, eachsecsections, said sections being proportioned electrically relative toeach other and relative to said electrical connections that thedielectric material of the secions is operated at diilerent gradientsdiffering progressively substantially like and in the same order as saidprogressively larger heat-dissipating surfaces.

11. In condenser construction, in combination, a plurality of condensersections each comprising plate members alternated with dielectric ma;terial, said sections being connected in series, certain of saidsections having a larger heat-dissipating surface than others and theelectrostatic capacity of said sections being substantially the samethroughout, the thickness of the dielectric material being smaller forsections of larger heatdissipating surface than for sections of smallerheat-dissipating surface.

12. In condenser construction, in combination, a plurality of condensersections each comprising plate -members alternated with dielectricmaterial, said sections being connected in series, certain of saidsections having a larger heat-dissipating surface than others and thethickness of dielectric material being substantially the same gthroughout, said sections being so proportioned that the voltage appliedthereto causes the operating gradient of the dielectric material of thesections of larger heat-dissipating surface to be higher than theoperating gradient of the dielectric material of sections of smallerheat-dissipating surface.

13. A condenser made up of a plurality of electrically connectedsections eachA made up of plate members and dielectric materialalternated, the dielectric'material employed per k. v. a. in saidsections being determined substantially by its dielectric strength aloneand said sections having heat dissipating surfaces larger than would benecessary if heat losses in the dielectric material, at the frequency ofoperation of the condenser, were considered a factor in determining thevolume of the dielectric material employed.

BROR G. OLVING.

